Spinocerebellar ataxias (SCA) are a heterogeneous group of disorders characterized by degeneration of the cerebellum and its connections with various levels of cerebral, extrapyramidal, bulbar, spinal and peripheral nervous system involvement. Previous studies investigating non-motor symptoms in patients with SCA found a high prevalence of urinary symptoms in patients with SCA1, SCA2, SCA3 and SCA6. However, there are only few studies that were directly aimed at assessing and characterising lower urinary tract (LUT), bowel and sexual symptoms in patients with SCA. Moreover, data regarding the clinical characteristics that could predict lower urinary tract dysfunction in patients with SCA are lacking.
The aim of this study was to assess the prevalence, characteristics and impact on quality of life of lower urinary tract and bowel dysfunction in patients affected by the most common autosomal dominant inherited SCAs. Moreover, this study aimed to assess the possible clinical predictors of lower urinary tract dysfunction.

This was a cross-sectional study in patients with genetically determined SCA1, 2, 3, 6 and 7, attending a tertiary centre for neurological diseases (National Hospital for Neurology and Neurosurgery, Queen Square, London, UK). Demographic data were collected. Characteristics and severity of clinical symptoms were assessed using the Scale for the Assessment and Rating of Ataxia (SARA) and Inventory of Non-Ataxia Symptoms (INAS). Patients were asked to complete the following questionnaires to assess the bladder, bowel and sexual dysfunction and quality of life: Urinary Symptom Profile (USP), International Prostate Symptom Score (I-PSS), SF-Qualiveen and Neurogenic Bowel Dysfunction (NBD). Data regarding bladder management were collected and some patients underwent urodynamics testing.

65 patients with SCA were invited to take part in the study but only 50 accepted to complete the assessments. Of these, 4 patients were affected by SCA1, 5 by SCA2, 13 by SCA3, 17 by SCA6 and 5 by SCA7. 
30 patients (60%) self-reported urinary complaints during the clinical assessment, with a higher prevalence of bladder symptoms in patients with SCA7 (83.3%) and SCA3 (61.5%) compared to SCA1 and SCA2 (50%). The median duration of urinary symptoms was 5.0 years, being higher in SCA7 and SCA6 groups (13.0 and 9.0 years,  respectively).
With regards to USP questionnaire, only 9 patients (18% - 4 affected by SCA2 , 2 by SCA3, 2 by SCA6 and 1 by SCA7) had a score of 0, indicating absence of any urinary symptoms. The median scores of the different sections of USP were the following: stress incontinence 0.9, overactive bladder (OAB) 4.71 and low stream (LS)  1.1. 40 patients (81.6%) scored at least 1 point in the OAB score, and 18 patients (36,7%) in the LS score. Urinary frequency and urgency were the most common complaints (both n=33, 67.3%), followed by incontinence and nocturia (both n=15, 30.6%).
9 patients underwent pressure flow urodynamic studies; of these, 2 were affected by SCA 7 and 7 by SCA3. With regards to patients with SCA3: detrusor overactivity was found in 6 (85.7%) and acontractile detrusor in 1 patient; mean detrusor pressure at maximum flow (Pdet at Qmax) was 36.33 cmhH2O (SD 20.89), mean bladder capacity was 307.4 ml (SD 199.29), mean volume at first desire to void (FDV) was 153.75 ml (SD 97.1). Free uroflowmetry showed mean PVR of 90.29 ml (SD 121.1), mean Qmax 20.15 ml/s (SD 8.77) and mean voided volume 221.62 ml (SD 185.25). According to the bladder outlet obstruction (BOO) index, three patients were categorized as equivocal and three as unobstructed (data were not available for one patient).  With regards to patients with SCA7: no detrusor overactivity was found; mean detrusor pressure at maximum flow (Pdet at Qmax) was 46.5 cmH2O (SD 17.68), mean bladder capacity was 222 ml (SD 124.45), mean volume at first desire to void (FDV) was 175.5 ml (SD 99.7). Free uroflowmetry showed mean PVR of 58.75 ml (SD 85.62) and mean voided volume 127.3 ml (SD 86.07). One patient was categorized as obstructed according to the BOO index (data were not available for one patient).
Patients with self-reported LUTS were significantly older (61.83 vs 51.70, p=0.021) and their ataxia was more severe (mean SARA score 15.793 vs 9.525, p=0.05). 
Linear regression analysis showed that duration of ataxia was a determinant in severity of LUTS (p=0.024). Bowel complaints were less common (n=6; 12 %) and, when present, were mild in severity (mean NBD score 0.82; SD 1.6). Mean score of SF Qualiveen was 1.08 (SD 1.22); patients with SCA2, SCA 6 and SCA7 had lower scores (0.45, 0.7 and 1.10 respectively), indicating better quality of life, while those with SCA1 and 3 had higher scores (3.03 and 1.43 respectively).  
Management of LUTS included oral medications (antimuscarinics (n=9; 18%) or Mirabegron (n=1; 2%), tamsulosin, (n=1; 2%)), percutaneous tibial nerve stimulation (n=1; 2%) and intermittent self catheterisation (n=1; 2%), non-pharmacological measures (n=19, 38%).

A large proportion of patients with SCA experience LUTS and the duration of ataxia appears to be a determinant in their severity. Previous studies have reported high prevalence of LUTS and urodynamics abnormalities in patients with SCA 3, 6 and Friedreich’s ataxia (1,2,3,).  
Only a small proportion of patients were on treatment and the most commonly used agents were antimuscarinics. 
Common urodynamics findings were detrusor overactivity (85.7% of patients with SCA 3) and BOO due to functional obstruction caused by detrusor-sphincter dyssinergia, possibly related to pyramidal tract involvement.
The urinary disturbances in patients with SCA are multi-factorial, possibly due to the involvement of the cerebellum, spinocerebellar pathways, pyramidal tracts and peripheral nervous system. 
Bowel dysfunction was less common (only 12% of patients).

LUTS are extremely common in patients affected by SCA and have a significant impact on quality of life but they are still under-recognized and under-treated.  The severity of LUTS increases with greater disease duration. 
Assessment and treatment of LUTS is of paramount importance in these patients.

Lad M, Parkinson MH, Rai M, et al. Urinary, bowel and sexual symptoms in a cohort of patients with Friedreich's ataxia. Orphanet J Rare Dis. 2017;12(1):158. Published 2017 Sep 26. doi:10.1186/s13023-017-0709-y
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